1. Technical Field of the Invention
The present invention relates to contactless tags including Radio Frequency IDentification (RFID) integrated circuits (IC)s and RFID tags. In particular, the present invention relates to a contactless-tag electronic circuit and a contactless tag.
2. Description of the Related Art
A typical contactless-tag electronic circuit includes an antenna coil, or a transceiving device, that receives data for communication with a reader/writer. In the typical electronic circuit, a power supply circuit rectifies and smoothes an alternating-current wave received by an antenna coil.
A contactless-tag electronic circuit including a display unit, such as an electrophoretic display or a liquid crystal display (LCD), and a memory is desirable in some cases. In such cases, a display unit or the like capable of display for a required period of time, even when a contactless tag is distant from a reader, is desirable. In this electronic circuit, therefore, a power supply circuit requires a booster circuit using a primary battery or a secondary battery for voltage boosting. The booster circuit may be a charge pump booster having a combination of capacitors and transistors without using a booster coil. However, a plurality of transistors are required, thus increasing the IC area and the cost. In a booster circuit using the booster coil, on the other hand, the booster coil must be separately disposed, thus increasing the cost.
The present invention has been made in view of the foregoing problems with the conventional electronic circuit, and it is an advantage of the present invention to provide a low-cost electronic circuit for a contactless tag that requires no separate booster coil even when a display and a memory are disposed in the electronic circuit.